Abstract
Background and Aims
Decreased exercise capacity due to muscle weakness and exercise intolerance reduces the ability to perform activities of daily living in patients with end-stage kidney disease. Data on exercise type in dialysis population and its muscle effects are scarce. We aimed to determine the impact of training type (strength, resistance and mixed) on cardiovascular performance, muscle function (strength-speed parameters, electrophysiological function of muscles) in patients on hemodialysis maintenance.
Method
Eighty six dialysis patients underwent claster randomisation and were assigned to an exercise intervention groups: A - controlled endurance training during haemodialysis using rotors (MOTOmed letto2), B - controlled force training (resistance), C - Tai Chi training on non dialysis days. Intervention lasted 6 months, 3 times a week (A, B) and 2 times a week (C) for 60 minutes. The outcome measures were spiroergometry (VO2/VO2max), strength of the lower limbs and electromyographic examination. Values at the baseline and 6 months later were compared.
Results
45 patients completed intervention period and were analysed. Mean age in group A was 64±12y (n-16), in B was 60,5±10y. (n-15) and in C – 68,5±9y. (n-14). Patients did not differ markedly between groups in term of sex, BMI, dialysis vintage and comorbidities.
After 6 months of training, VO2 and VO2max increased significantly only in group B (resistance training) Δ12.7 % for VO2 and 12.9% for VO2max but not in A and C group (Fig.1.). Regarding force torque of quadriceps (ΔPT) in isometric conditions the highest peak values were measured in group B (resistance training), namely increase by 13.6% (p=0.0004) in right (R) and 14% (p<0.0001) in left (L); in group A (endurance) 3.2% in R and 3.7% in L; in group C (Tai Chi group) by 7% (p<0.05) in R and 6.8% (p<0.05) in L. In terms of changes in electrophysiological function of right (QEMG_R) and left (QEMG_L) quadriceps, there were increases: for group A by 10.5% (p<0.0001) and 9.6% (p<0.05); B 9.7% (p=0.0002) and 20.1% (p=0.0001); for C by 4.5% and 6.2% for R and L, respectively (Fig.2).
In groups B and C significant increases in static force moments (Δ%PT) was associated with increases in electrophysiological action (Δ%QEMG), but in group A increase in EMG activity did not correspond with rise in muscle force (Fig.2).
Conclusion
Differences in muscle strength and functions were observed after 6 months of various type of exercise intervention in dialysis patients. Resistance training during dialysis showed the largest improvement in cardiorespiratory function and isometric leg muscle strength.